Automatic service function validation in a virtual network environment

ABSTRACT

Systems, methods, and computer-readable media for improving the reliability of service function (SF) application in a service function chain (SFC) are provided. In some aspects, the subject technology facilitates automatic service function type validation by a service function forwarder (SFF), for example, by using a probe configured to query a function type of a SF module associated with the validating SFF.

TECHNICAL FIELD

The disclosed technology relates to methods and systems for improving the reliability of service function (SF) instantiation in a service function chain (SFC), for example that is deployed in a software defined network (SDN) or network function virtualization (NFV) environment. In particular, the subject technology provides ways for a service function forwarder (SFF) to validate a service function type implemented by a service function module (SF module) by initiating a probe to query and validate the function type of the SF module.

BACKGROUND

Network Function Virtualization (NFV) technology, in combination with Software Defined Networking (SDN), promises to help transform today's carrier networks. It will transform how they are deployed and managed, and the way services are delivered. Some ultimate goals are to enable service providers to reduce costs, increase business agility, and accelerate the time to market of new services.

The utilization of NFV and SDN technologies allows the decoupling of network functions from underlying hardware so they run as software images or logical modules on commercial off-the-shelf and purpose-built hardware. The NFV does so by using virtualization technologies (computers, networks, and storage media) to virtualize the network functions. The objective is to reduce the dependence on dedicated physical devices by allocating and using the physical and virtual resources only when and where needed. With this approach, service providers can reduce overall costs by shifting components to a common physical infrastructure while optimizing its use, allowing them to respond more dynamically to changing market demands by deploying new applications and services as needed. The virtualization of network functions accelerates the time to market for new services by allowing for more automated and streamlined approaches to service delivery.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which the above-recited and other advantages and features of the disclosure can be obtained, a more particular description of the principles briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only example aspects of the disclosure and are not therefore to be considered to be limiting of its scope, the principles herein are described and explained with additional specificity and detail through the use of the accompanying drawings in which:

FIG. 1 illustrates a diagram of an example virtual network environment, according to some aspects of the subject technology.

FIG. 2A illustrates a conceptual diagram of a service function chain (SFC), according to some aspects of the technology.

FIG. 2B illustrates an example comparison table that can be used to validate a service function type (e.g., of one or more service function modules) in a SFC, according to some aspects of the subject technology.

FIG. 3 illustrates steps that can be used to implement an example service function type validation method, according to some aspects of the technology.

FIG. 4 illustrates an example of a network device.

FIGS. 5A and 5B illustrate example system embodiments.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Various embodiments of the disclosure are discussed in detail below. While specific implementations are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without parting from the spirit and scope of the disclosure.

Overview

Additional features and advantages of the disclosure will be set forth in the description which follows, and in part will be obvious from the description, or can be learned by practice of the herein disclosed principles. The features and advantages of the disclosure can be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features of the disclosure will become more fully apparent from the following description and appended claims, or can be learned by the practice of the principles set forth herein.

Description

A “service function module” (SF module), or “SF instance” can be implemented using a combination of hardware and/or software solutions, physical or virtual. As discussed in further detail below, service function (SF) invocation on a SF module can be facilitated using a service function forwarder (SFF), for example that is configured to receive a packet, make a determination regarding an applicable service function type, and based on the determination, may forward the packet to the appropriate SF module for function invocation. Similar to other virtualized network components, as used herein, a SFF can be a logical module implemented using a variety of hardware and software solutions, physical or virtual. For example, SF and SFF modules can be implemented by software routines executed on the same (or different) virtual machines (VMs), or may be executed in separate logical environments for example, running on different VMs and located at geographically disparate locations. As further used herein, an ordered set of SF invocations can be referred to as a “service function chain” (SFC).

While SFCs are routinely used to facilitate the ordered execution of predetermined service functions on traffic flows, conventional SF and SFF modules do not provide a way to diagnose service function errors that can occur between a given SFF and associated SFs. That is, there is no way to identify when an incorrect function type is applied by one or more SF modules in a SFC (e.g., chaining errors), or if incorrect connectivity is applied between two SF modules.

For example, a given SFF may be programmed to utilize an associated SF module, to perform a firewall function. However, if the SF module was incorrectly programmed to invoke an unexpected function type (e.g., a load balancing function), there would be no way for SFF to diagnose this error before/while forwarding the packet to the SF module. In implementations where a packet returned from the SF module is unchecked and forwarded (e.g., to the next hop) by the SFF, security problems may result.

Aspects of the subject technology address the foregoing problems by providing ways in which a service function forwarder (SFF) can perform SF function (type) validation on a corresponding SF module. As discussed in further detail below, the process of SF function validation may be performed automatically, for example, as a result of a new SF instantiation, or as a result of detected changes to a SFF forwarding database, or as a result of detected changes in network parameters, such as detected changes to SF function type programming, or as a result of other changes made, for example, by a system administrator via a controller. As also discussed further below, SF type validation performed by a SFF can be accomplished using a probe, such as, a single-hop SFC traceroute packet designed for transmission from the SFF to a corresponding SF module to query a function type for at least one function implemented by the SF module, for example, corresponding with a particular service path identifier (SPI) and service index limit (SIL).

FIG. 1 illustrates a diagram of an example virtual network environment 100 in which one or more service function chains can be implemented. Fabric 112 can represent the underlay (i.e., physical network) of network environment 100. Fabric 112 can include spine routers 1-N (102 _(A-N)) (collectively “102”) and leaf routers 1-N (104 _(A-N)) (collectively “104”). Leaf routers 104 can reside at the edge of fabric 112, and can thus represent the physical network edges. Leaf routers 104 can be, for example, top-of-rack (“ToR”) switches, aggregation switches, gateways, ingress and/or egress switches, provider edge devices, and/or any other type of routing or switching device.

Leaf routers 104 can be responsible for routing and/or bridging tenant or endpoint packets and applying network policies. Spine routers 102 can perform switching and routing within fabric 112. Thus, network connectivity in fabric 112 can flow from spine routers 102 to leaf routers 104, and vice versa.

Leaf routers 104 can provide servers 1-4 (106 _(A-D)) (collectively “106”), hypervisors 1-4 (108 _(A)-108 _(D)) (collectively “108”), virtual machines (VMs) 1-4 (110 _(A)-110 _(D)) (collectively “110”), collectors 118, engines 120, and the Layer 2 (L2) network access to fabric 112. For example, leaf routers 104 can encapsulate and decapsulate packets to and from servers 106 in order to enable communications throughout environment 100. Leaf routers 104 can also connect other network-capable device(s) or network(s), such as a firewall, a database, a server, etc., to the fabric 112. Leaf routers 104 can also provide any other servers, resources, endpoints, external networks, VMs, services, tenants, or workloads with access to fabric 112.

VMs 110 can be virtual machines hosted by hypervisors 108 running on servers 106. VMs 110 can include workloads running on a guest operating system on a respective server. Hypervisors 108 can provide a layer of software, firmware, and/or hardware that creates and runs the VMs 110. Hypervisors 108 can allow VMs 110 to share hardware resources on servers 106, and the hardware resources on servers 106 to appear as multiple, separate hardware platforms. Moreover, hypervisors 108 and servers 106 can host one or more VMs 110. For example, server 106 _(A) and hypervisor 108 _(A) can host VMs 110 _(A-B).

In some cases, VMs 110 and/or hypervisors 108 can be migrated to other servers 106. For example, VM 110 _(A) can be migrated to server 106 _(C) and hypervisor 108 _(B). Servers 106 can similarly be migrated to other locations in network environment 100. For example, a server connected to a specific leaf router can be changed to connect to a different or additional leaf router. In some cases, some or all of servers 106, hypervisors 108, and/or VMs 110 can represent tenant space. Tenant space can include workloads, services, applications, devices, and/or resources that are associated with one or more clients or subscribers. Accordingly, traffic in network environment 100 can be routed based on specific tenant policies, spaces, agreements, configurations, etc. Moreover, addressing can vary between one or more tenants. In some configurations, tenant spaces can be divided into logical segments and/or networks and separated from logical segments and/or networks associated with other tenants.

As discussed in further detail below, VMs 110 can be used to implement one or more service chains SFCs (not illustrated).

FIG. 2A illustrates an example environment 200 for implementing a service function chain (SFC) 204. Environment 200 includes server 202, which is configured to implement SFC 204; however, it is understood that one or more hardware or software components of SFC 204 can be implemented by one or more of logical modules on server 202, or on physically distinct hardware, for example, on one or more servers 106 represented by environment 100, discussed above.

In environment 200, SFC 204 includes classifier 206 and a plurality of service function forwarders (SFFs), i.e., SFF1, SFF2, and SSF3 (208A-212A). Each SFF is associated with a respective SF module, i.e., SF1_FW, SF2_LB, and SF3_DPI (208B-212B), that is configured to apply a particular function type to any received packets/data flows. In some aspects, a given SF module may be configured to apply multiple functions, for example, of different function types. By way of example, in environment 200 SF1 (208B) is associated with a “firewall” function, SF2 (210B) is associated with a “load balancing” function, and SF3 (212B) is associated with a “deep packet inspection” function, respectively. Although the example of environment 200 illustrates each SFF (e.g., 208A-212A) as paired with a single SF module (e.g., 208B-212B), it is understood that each SFF may be communicatively coupled to two or more SF modules, without departing from the scope of the subject technology.

In practice, a packet received by classifier 206 is encapsulated to include header information that corresponds with an ordered set of service functions to be applied by function chain 204. However, as discussed above, incorrect service function types applied at one or more of the SF modules (e.g., 208B-212B), can cause a failure of SFC 204, and present potential security issues.

To prevent incorrect service function type invocation in SFC 204, aspects of the subject technology provide ways in which each SFF (208A-212A) can automatically validate one or more function types invoked by a corresponding SF module (e.g., 208B-212B).

In some aspects, each SFF (208A-212A) can be configured to automatically validate a function type for each of one or more service functions implemented by its corresponding SF module (208B-112B), for example, in response to a detected change in one or more network parameters. By way of example, changes in network parameters that can cause service function validation may include, but are not limited to, one or more of the following: changes to one or more SF modules 208B-212B (for example, resulting from instantiation of a new SF type), changes to one or more SFFs 208A-212A (for example, resulting from changes to a SFF forwarding database), and/or detected changes to other network components or modules, for example, resulting from instructions received by a controller (not illustrated).

In practice, service function type validation by a SFF can be accomplished by issuing a probe to a SF module wherein the probe is configured to query the SF module's function type. In some aspects, the probe may include a modified-traceroute that is configured to query the function type implemented by the SF module. In cluster implementations, SFF would issue a probe for each SF module of the cluster. To validate the function type, the function type reported by the SF module can be compared to an expected function type by the requesting SFF, for example, that is stored in a comparison table, as explained in further detail with respect to FIG. 2B, discussed below.

By way of example, the SFF can compare the function type reported by the SF module to a forwarding table or comparison table that includes SF module/function-type pairs. In case an SF module having more than one Service Functions, comparison table would have independent SF module/function-type pair entry. Depending on implementation, the comparison table can be stored locally, or may be referenced/called from another physical or logical network element.

If the SF module's function type is successfully validated, the validating SFF can permit the packet/traffic flow to be transmitted to the next hop, e.g., a next SFF destination in the SFC. Alternatively, invalid function-type invocation can cause the SFF to drop packets, for example, to avoid security breaches that may result from improperly directed traffic flows.

In some aspects, an SFF validating a function type for one or more SF modules can cause the SFF to generate a log detailing aspects of the validation result. For example, the SFF may save various details to a failure log including identifying information of the SF module, an expected function type corresponding with the failed SF module, and/or the actual function type currently implemented on the SF module, and the like.

By way of example, the SF module, upon receiving the SFF generated probe, would check for SF type(s) enabled, and convey the existence of each of SF types in its reply to SFF.

FIG. 2B illustrates an example of a comparison table (e.g., a “forwarding database”) that can be utilized by a SFF for performing service function type validation. In the illustrated example, SFF1 (208A) includes comparison table 209A, which can be locally stored to a memory module that is shared, or accessible by, SFF1. In other implementations comparison table 209A can reside at a memory location physically or logically remote from SFF1, such as on another virtual machine or physical node.

As illustrated, comparison table 209A contains fields including: SPI (for “service path identifier”), SI (for “service index”), NH (for “next hop”), and “type,” for example, which indicates an expected service function type for the associated SFF. That is, comparison table 209A can be used to maintain a function type value (indicating a function type) for each SI or service next hop. As discussed in further detail below, comparison of a reported service function type (e.g., by a SF module), with the corresponding “type” indicated by comparison table 209A can be used to validate the service function type being invoked by the reporting SF module. In some aspects, function type values can be updated in response to a message, for example, that is received from an external controller or API (not illustrated).

FIG. 3 illustrates steps of an example method for implementing a service function type validation. The method begins with step 300 in which a probe is initiated (e.g., from a SFF), wherein the probe includes a modified-traceroute configured to query a function type of a corresponding SF module.

As discussed above, initiation of the probe can result from detected changes throughout the network, including but not limited to: changes to one or more SF modules, e.g., 208B-212B, for example, resulting from instantiation of a new SF type, changes to one or more SFFs 208A-212A, for example, resulting from changes to a SFF forwarding database, and/or detected changes to other network components or modules that can result from instructions received by a controller (not illustrated). Is understood that other events or conditions may trigger service function validation for one or more SF modules, without departing from the scope of the technology.

The modified traceroute can be a traceroute packet configured for a single “hop” through the network, i.e., transmitted from an originating SFF to a respective SF module with a destination address pointed to the originating SFF. In some aspects, the modified traceroute can contain a service function chain (SFC) request configured to elicit the insertion of a service function type by the receiving SF module. By way of example, the SFC request can include a service function index that is set to a service index limit (SIL), which can elicit the insertion of the function type into a return packet (reply) provided by the SF module.

Subsequently, in step 302 the SFF receives a reply from the SF module. In some aspects the reply may be a return of one or more modified traceroute packets originally sent from the SFF to the SF module. As indicated above, the reply includes an indication of the function being invoked by the transmitting service function module (i.e., the function type). Further to the example illustrated environment 200 (discussed above), a reply provided by SF2 (210B) would indicate that a “load balancing” function is currently implemented by SF2 210B.

In step 304, the function type of the SF module is validated based on the reply. Service function type validation can be performed, for example, by comparing a service function type indicated in the reply with a table indicating associations between one or more service function modules and their respective function types (e.g., comparison table 209A, discussed above). The comparison table may reside locally, i.e., with the validating SFF; alternatively, the comparison table can be stored at another logical/physical module in the network.

In step 306, the SFF determines whether to permit packet forwarding based on the function type of the corresponding SFF module. In instances where the reported service function type corresponds with an expected service function type in the comparison table, traffic flows are forwarded from the validating SFF to a subsequent network destination, such as the next SFF in the service function chain. By way of example, referring to environment 200 of FIG. 2A, a valid function type (i.e., “firewall”) for SF1 (208B) would enable corresponding SFF1 (208A) to forward the traffic flow onto SFF2 (210A).

Alternatively, if the SFF is unable to validate the function type of its corresponding SF module, packets can be dropped to prevent forwarding of unchecked data through the network. By preventing traffic flows from emanating from validation failure points in the SFC, the subject technology reduces the risk of security breaches that can occur from incorrect function chaining.

FIG. 4 illustrates an example network device 410 according to some embodiments. Network device 410 includes a master central processing unit (CPU) 462, interfaces 468, and a bus 415 (e.g., a PCI bus). When acting under the control of appropriate software or firmware, the CPU 462 is responsible for executing packet management, error detection, and/or routing functions. The CPU 462 preferably accomplishes all these functions under the control of software including an operating system and any appropriate applications software. CPU 462 may include one or more processors 463 such as a processor from the Motorola family of microprocessors or the MIPS family of microprocessors. In an alternative embodiment, processor 463 is specially designed hardware for controlling the operations of router 410. In a specific embodiment, a memory 461 (such as non-volatile RAM and/or ROM) also forms part of CPU 462. However, there are many different ways in which memory could be coupled to the system.

The interfaces 468 are typically provided as interface cards (sometimes referred to as “line cards”). Generally, they control the sending and receiving of data packets over the network and sometimes support other peripherals used with the router 410. Among the interfaces that can be provided are Ethernet interfaces, frame relay interfaces, cable interfaces, DSL interfaces, token ring interfaces, and the like. In addition, various very high-speed interfaces can be provided such as fast token ring interfaces, wireless interfaces, Ethernet interfaces, Gigabit Ethernet interfaces, ATM interfaces, HSSI interfaces, POS interfaces, FDDI interfaces and the like. Generally, these interfaces may include ports appropriate for communication with the appropriate media. In some cases, they may also include an independent processor and, in some instances, volatile RAM. The independent processors may control such communications intensive tasks as packet switching, media control and management. By providing separate processors for the communications intensive tasks, these interfaces allow the master microprocessor 462 to efficiently perform routing computations, network diagnostics, security functions, etc.

Although the system shown in FIG. 4 is one specific network device of the present invention, it is by no means the only network device architecture on which the present invention can be implemented. For example, an architecture having a single processor that handles communications as well as routing computations, etc. is often used. Further, other types of interfaces and media could also be used with the router.

Regardless of the network device's configuration, it may employ one or more memories or memory modules (including memory 461) configured to store program instructions for the general-purpose network operations and mechanisms for roaming, route optimization and routing functions described herein. The program instructions may control the operation of an operating system and/or one or more applications, for example. The memory or memories may also be configured to store tables such as mobility binding, registration, and association tables, etc.

FIG. 5A and FIG. 5B illustrate example system embodiments. The more appropriate embodiment will be apparent to those of skill in the art when practicing the present technology. Persons of ordinary skill in the art will also readily appreciate that other system embodiments are possible.

FIG. 5A illustrates a system bus computing system architecture 500 wherein the components of the system are in electrical communication with each other using a bus 505. Exemplary system 500 includes a processing unit (CPU or processor) 510 and a system bus 505 that couples various system components including the system memory 515, such as read only memory (ROM) 520 and random access memory (RAM) 525, to the processor 510. The system 500 can include a cache of high-speed memory connected directly with, in close proximity to, or integrated as part of the processor 510. The system 500 can copy data from the memory 515 and/or the storage device 530 to the cache 512 for quick access by the processor 510. In this way, the cache can provide a performance boost that avoids processor 510 delays while waiting for data. These and other modules can control or be configured to control the processor 510 to perform various actions. Other system memory 515 can be available for use as well. The memory 515 can include multiple different types of memory with different performance characteristics. The processor 510 can include any general purpose processor and a hardware module or software module, such as module 1 532, module 2 534, and module 3 536 stored in storage device 530, configured to control the processor 510 as well as a special-purpose processor where software instructions are incorporated into the actual processor design. The processor 510 may essentially be a completely self-contained computing system, containing multiple cores or processors, a bus, memory controller, cache, etc. A multi-core processor can be symmetric or asymmetric.

To enable user interaction with the computing device 500, an input device 545 can represent any number of input mechanisms, such as a microphone for speech, a touch-sensitive screen for gesture or graphical input, keyboard, mouse, motion input, speech and so forth. An output device 535 can also be one or more of a number of output mechanisms known to those of skill in the art. In some instances, multimodal systems can enable a user to provide multiple types of input to communicate with the computing device 500. The communications interface 540 can generally govern and manage the user input and system output. There is no restriction on operating on any particular hardware arrangement and therefore the basic features here may easily be substituted for improved hardware or firmware arrangements as they are developed.

Storage device 530 is a non-volatile memory and can be a hard disk or other types of computer readable media which can store data that are accessible by a computer, such as magnetic cassettes, flash memory cards, solid state memory devices, digital versatile disks, cartridges, random access memories (RAMs) 525, read only memory (ROM) 520, and hybrids thereof.

The storage device 530 can include software modules 532, 534, 536 for controlling the processor 510. Other hardware or software modules are contemplated. The storage device 530 can be connected to the system bus 505. In one aspect, a hardware module that performs a particular function can include the software component stored in a computer-readable medium in connection with the necessary hardware components, such as the processor 510, bus 505, display 535, and so forth, to carry out the function.

FIG. 5B illustrates an example computer system 550 having a chipset architecture that can be used in executing the described method and generating and displaying a graphical user interface (GUI). Computer system 550 is an example of computer hardware, software, and firmware that can be used to implement the disclosed technology. System 550 can include a processor 555, representative of any number of physically and/or logically distinct resources capable of executing software, firmware, and hardware configured to perform identified computations. Processor 555 can communicate with a chipset 560 that can control input to and output from processor 555. In this example, chipset 560 outputs information to output device 565, such as a display, and can read and write information to storage device 570, which can include magnetic media, and solid state media, for example. Chipset 560 can also read data from and write data to RAM 575. A bridge 580 for interfacing with a variety of user interface components 585 can be provided for interfacing with chipset 560. Such user interface components 585 can include a keyboard, a microphone, touch detection and processing circuitry, a pointing device, such as a mouse, and so on. In general, inputs to system 550 can come from any of a variety of sources, machine generated and/or human generated.

Chipset 560 can also interface with one or more communication interfaces 590 that can have different physical interfaces. Such communication interfaces can include interfaces for wired and wireless local area networks, for broadband wireless networks, as well as personal area networks. Some applications of the methods for generating, displaying, and using the GUI disclosed herein can include receiving ordered datasets over the physical interface or be generated by the machine itself by processor 555 analyzing data stored in storage 570 or 575. Further, the machine can receive inputs from a user via user interface components 585 and execute appropriate functions, such as browsing functions by interpreting these inputs using processor 555.

It can be appreciated that example systems 500 and 550 can have more than one processor 510 or be part of a group or cluster of computing devices networked together to provide greater processing capability.

For clarity of explanation, in some instances the present technology may be presented as including individual functional blocks including functional blocks comprising devices, device components, steps or routines in a method embodied in software, or combinations of hardware and software.

In some embodiments the computer-readable storage devices, mediums, and memories can include a cable or wireless signal containing a bit stream and the like. However, when mentioned, non-transitory computer-readable storage media expressly exclude media such as energy, carrier signals, electromagnetic waves, and signals per se.

Methods according to the above-described examples can be implemented using computer-executable instructions that are stored or otherwise available from computer readable media. Such instructions can comprise, for example, instructions and data which cause or otherwise configure a general purpose computer, special purpose computer, or special purpose processing device to perform a certain function or group of functions. Portions of computer resources used can be accessible over a network. The computer executable instructions may be, for example, binaries, intermediate format instructions such as assembly language, firmware, or source code. Examples of computer-readable media that may be used to store instructions, information used, and/or information created during methods according to described examples include magnetic or optical disks, flash memory, USB devices provided with non-volatile memory, networked storage devices, and so on.

Devices implementing methods according to these disclosures can comprise hardware, firmware and/or software, and can take any of a variety of form factors. Typical examples of such form factors include laptops, smart phones, small form factor personal computers, personal digital assistants, rackmount devices, standalone devices, and so on. Functionality described herein also can be embodied in peripherals or add-in cards. Such functionality can also be implemented on a circuit board among different chips or different processes executing in a single device, by way of further example.

The instructions, media for conveying such instructions, computing resources for executing them, and other structures for supporting such computing resources are means for providing the functions described in these disclosures.

Although a variety of examples and other information was used to explain aspects within the scope of the appended claims, no limitation of the claims should be implied based on particular features or arrangements in such examples, as one of ordinary skill would be able to use these examples to derive a wide variety of implementations. Further and although some subject matter may have been described in language specific to examples of structural features and/or method steps, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to these described features or acts. For example, such functionality can be distributed differently or performed in components other than those identified herein. Rather, the described features and steps are disclosed as examples of components of systems and methods within the scope of the appended claims. Moreover, claim language reciting “at least one of” a set indicates that one member of the set or multiple members of the set satisfy the claim.

It should be understood that features or configurations herein with reference to one embodiment or example can be implemented in, or combined with, other embodiments or examples herein. That is, terms such as “embodiment”, “variation”, “aspect”, “example”, “configuration”, “implementation”, “case”, and any other terms which may connote an embodiment, as used herein to describe specific features or configurations, are not intended to limit any of the associated features or configurations to a specific or separate embodiment or embodiments, and should not be interpreted to suggest that such features or configurations cannot be combined with features or configurations described with reference to other embodiments, variations, aspects, examples, configurations, implementations, cases, and so forth. In other words, features described herein with reference to a specific example (e.g., embodiment, variation, aspect, configuration, implementation, case, etc.) can be combined with features described with reference to another example. Precisely, one of ordinary skill in the art will readily recognize that the various embodiments or examples described herein, and their associated features, can be combined with each other.

A phrase such as an “aspect” does not imply that such aspect is essential to the subject technology or that such aspect applies to all configurations of the subject technology. A disclosure relating to an aspect may apply to all configurations, or one or more configurations. A phrase such as an aspect may refer to one or more aspects and vice versa. A phrase such as a “configuration” does not imply that such configuration is essential to the subject technology or that such configuration applies to all configurations of the subject technology. A disclosure relating to a configuration may apply to all configurations, or one or more configurations. A phrase such as a configuration may refer to one or more configurations and vice versa. The word “exemplary” is used herein to mean “serving as an example or illustration.” Any aspect or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects or designs.

Moreover, claim language reciting “at least one of” a set indicates that one member of the set or multiple members of the set satisfy the claim. For example, claim language reciting “at least one of A, B, and C” or “at least one of A, B, or C” means A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B and C together. 

What is claimed is:
 1. A method for validating a service function type on a service function (SF) module, the method comprising: initiating a probe, at a service function forwarder (SFF), to query a function type of a corresponding SF module; receiving a reply from the corresponding SF module, in response to the probe, with an indication of an actual function being implemented by the corresponding SF module; validating, at the SFF, the function type of the corresponding SF module by determining whether the actual function corresponds with an expected service function type using a forwarding database, the forwarding database maintaining the expected service function type, having a plurality of updatable function type values with each of the updatable function type values indicating a type, and including multiple entries for the SF module if the SF module has multiple ones of the expected service function type; and determining, at the SFF, whether to permit packet forwarding, based on the function type of the corresponding SF module, wherein, if the function type is validated, the SFF permits a packet to be transmitted to a next hop, and if the function type is not validated, the SFF drops the packet.
 2. The method of claim 1, wherein initiating the probe further comprises: detecting, at the SFF, a change in service function instantiation at the corresponding SF module; and automatically initiating the probe in response to the change in service function instantiation.
 3. The method of claim 1, wherein initiating the probe further comprises: detecting, at the SFF, a change relative to the SFF; and automatically initiating the probe in response to the change relative to the SFF.
 4. The method of claim 1, wherein initiating the probe further comprises: generating a request for the corresponding SF module; setting a service path identifier (SPI) of the request to a service index limit (SIL) value; and forwarding the request to a forwarding address associated with the corresponding SF module.
 5. The method of claim 1, wherein receiving the reply from the corresponding SF module further comprises: determining if the reply comprises correct SPI and SIL values; and reading the function type from the reply.
 6. The method of claim 1, wherein the forwarding database includes a service index path, a service index, and a next hop.
 7. The method of claim 1, wherein the probe comprises a modified service function chain (SF) traceroute configured for a single-hop transmission to the corresponding SF module.
 8. A service function type validation system comprising: at least one processor; and a memory device storing instructions that, when executed by the at least one processor, cause the validation system to: initiate a probe, at a service function forwarder (SFF), wherein the probe is configured to query a function type of a corresponding SF module; receive a reply from the corresponding SF module, in response to the probe, with an indication of an actual function being implemented by the corresponding SF module; validate, at the SFF, the function type of the corresponding SF module by determining whether the actual function corresponds with an expected service function type using a forwarding database, the forwarding database maintaining the expected service function type, having a plurality of updatable function type values with each of the updatable function type values indicating a type, and including multiple entries for the SF module if the SF module has multiple ones of the expected service function type; and determine, at the SFF, whether to permit packet forwarding, based on the function type of the corresponding SF module, wherein, the SFF is configured to permit a packet to be transmitted to a next hop if the function type is validated, and the SFF is configured to drop the packet if the function type is not validated.
 9. The service function type validation system of claim 8, wherein initiating the probe further comprises: detecting, at the SFF, a change in service function instantiation at the corresponding SF module; and automatically initiating the probe in response to the change in service function instantiation.
 10. The service function type validation system of claim 8, wherein initiating the probe further comprises: detecting, at the SFF, a change relative to the SFF; and automatically initiating the probe in response to the change relative to the SFF.
 11. The service function type validation system of claim 8, wherein initiating the probe comprises: generating a service function chain request for the corresponding SF module; setting a service path identifier (SPI) of the request to a service index limit (SIL) value; and forwarding the request to an address associated with the corresponding SF module.
 12. The service function type validation system of claim 8, wherein receiving the reply from the corresponding SF module further comprises: determining if the reply comprises correct SPI and SIL values; and reading the function type from the reply.
 13. The service function type validation system of claim 8, wherein the forwarding database includes a service index path, a service index, and a next hop.
 14. The service function type validation system of claim 8, wherein the probe comprises a modified service function chain (SF) traceroute configured for a single-hop transmission to the corresponding SF module.
 15. A non-transitory computer-readable storage medium comprising instructions stored therein, which when executed by one or more processors, cause the processors to perform operations comprising: initiating a probe, at a service function forwarder (SFF), wherein the probe is configured to query a function type of a corresponding SF module; receiving a reply from the corresponding SF module, in response to the probe, with an indication of an actual function being implemented by the SF module; validating, at the SFF, the function type of the corresponding SF module by determining whether the actual function corresponds with an expected service function type using a forwarding database, the forwarding database maintaining the expected service function type, having a plurality of updatable function type values with each of the updatable function type values indicating a type, and including multiple entries for the SF module if the SF module has multiple ones of the expected service function type; and determining, at the SFF, whether to permit packet forwarding, based on the function type of the corresponding SF module, wherein, the SFF is configured to permit a packet to be transmitted to a next hop if the function type is validated, and the SFF is configured to drop the packet if the function type is not validated.
 16. The non-transitory computer-readable storage medium of claim 15, wherein initiating the probe further comprises: detecting, at the SFF, a change in service function instantiation at the corresponding SF module; and automatically initiating the probe in response to the change in service function instantiation.
 17. The non-transitory computer-readable storage medium of claim 15, wherein initiating the probe further comprises: detecting, at the SFF, a change relative to the SFF; and automatically initiating the probe in response to the change relative to the SFF.
 18. The non-transitory computer-readable storage medium of claim 15, wherein initiating the probe comprises: generating a request for the corresponding SF module; setting a service function index of the request to a service index limit (SIL) value; and forwarding the request to an address associated with the corresponding SF module.
 19. The non-transitory computer-readable storage medium of claim 15, wherein receiving the reply from the corresponding SF module further comprises: determining if the reply comprises correct SPI and SIL values; and reading the function type from the reply.
 20. The non-transitory computer-readable storage medium of claim 15, wherein the forwarding database includes a service index path, a service index, and a next hop. 